Remove unused import

Author: marcusmoore

app/Mail/CheckoutAssetMail.php

@@ -14,7 +14,6 @@
 use Illuminate\Mail\Mailables\Attachment;
 use Illuminate\Mail\Mailables\Content;
 use Illuminate\Mail\Mailables\Envelope;
-use Illuminate\Notifications\Messages\MailMessage;
 use Illuminate\Queue\SerializesModels;
 
 class CheckoutAssetMail extends Mailable